1. Technical Field
The present invention relates to a circuit for correcting vertical distortion of a display device and, more particularly, to a circuit for correcting vertical distortion on a large-sized screen of a display device by use of a minute horizontal pulse.
2. Related Art
With the development of technologies in the fields of electricity, electronics and applications such as multimedia, it is a tendency for the recent display devices to have a large-sized screen in order to display graphic images.
Enlargement of the screen in the display device means that larger screen size is adapted to a cathode ray tube (referred to as a "Braun tube") which is to generate the electron beams in response to video signals and cause them to strike the phosphor coating, creating a picture on the screen. As the screen size of the Braun tube or cathode ray tube (hereinafter, referred to as "CRT") becomes larger, the geometrical structure of the screen is altered in such a manner as to require a deflection capacity of the deflection yoke for deflecting the electron beams across the large screen.
Display monitors have typically been provided with circuitry for correcting vertical distortion in a display device. In such arrangements, a correction signal is fed into a vertical deflection yoke for trouble shooting the vertical distortion on the cathode ray tube (CRT) screen. However, the use of large-sized display devices mentioned above results in a problem. Specifically, it is difficult to have a variable range of a signal sufficient to eliminate vertical distortion in such large-sized display devices because a horizontal post current is overlapped with a vertical post current. I have found, therefore, that there is a need for the development of a circuit for correcting vertical distortion in a display device using a large-sized screen. In particular, there is a need for the development of circuitry for correcting vertical distortion in a display device using a large-sized screen with a minute current by overlapping a low horizontal deflection post current with a vertical post current and applying a resulting post current to a vertical deflection yoke.